Computers are increasingly being connected to other devices and computer networks. Fiber optic lines are commonly used to handle the large amount of data transfer at high data transfer rate. The optic signals carried over the fiber optics must be converted by an optical transceiver to convert the optical light signals to electronic signals to be usable by by a computer. Modern optical transceivers have been modularized with standard physical sizes, under standard electrical interface agreements and standard optical interface agreements. One of such standards agreements is the Small Form-factor Pluggable Multi-Source Agreement (SFP MSA).
Printed Circuit Board (PCB) is an important component in an optical transceiver. A PCB can include transmission and reception circuits that are essential to key functions of the optical transceiver. The increased functionality in data communications requires an increased number of functions to be included on the PCB of an optical transceiver module. On the other hand, the dimensions of optical transceiver modules have become increasingly smaller. It is a challenge for a PCB with decreased interior space to carry more electronic functions. Furthermore, the modular shape and the standard electrical and optical interfaces in optical transceiver module also limit the usable area of the PCB.
One approach to overcome the above problem is to decrease the Integrated Circuit (IC) chip sizes on the PCB by using more advanced IC technologies with deep sub-micron transistors. Another solution is to combine functions previously held on different IC chips into one single IC, making a System-on-a-Chip (SOC) IC. These approaches however rely on the developments of new IC chips. A modern sized SOC chip costs millions of dollars in development, and it usually takes a year or longer to produce such a chip. Thus the SOC approach is expensive and time consuming.
Another approach to overcome the above problem is to increase the usable area of the PCB in the optical transceiver. For example, an extended PCB can be vertically attached to the first PCB, resulting in a combined PCB with a bigger usable area.
It is therefore desirable for a Printed Circuit Board to hold more functions for a fixed working space. Additionally, it is also desirable to make the PCB easier and inexpensive to manufacture and more reliable in use.